let testPermission =[{
    name:'home',
    path:'/',
    children:[
        {
            name:'about',
            path:'/about'
        }

    ]
}]

let testPermission2 = testPermission.filter((item)=>item.path==='/')[0]
testPermission2.children=testPermission2.children.concat({name:'test',path:'test'})

console.log(testPermission[0].children)